A New Approach to Robust and Fault Tolerant Control

In this paper, we shall summarize a new approach to robust and fault tolerant control proposed recently by the author. This approach is based on a variation of all controller parametrization. This robust and fault-tolerant control design consists of two parts: a nominal performance controller and a robustness controller, and works in such a way that when a component (sensor,actuator, etc.) failure is detected, the controller structure is reconfigured by adding a robustness loop to compensate the fault. We shall illustrate how this strategy works under various situations.

Robust fault-tolerant controller design for linear time-invariant systems with actuator failures:an indirect adaptive method

In this paper,indirect adaptive state feedback control schemes are developed to solve the robust fault-tolerant control （FTC） design problem of actuator fault and perturbation compensations for linear time-invariant systems.A more general and practical model of actuator faults is presented.While both eventual faults on actuators and perturbations are unknown,the adaptive schemes are addressed to estimate the lower and upper bounds of actuator-stuck faults and perturbations online,as well as to estimate control effectiveness on actuators.Thus,on the basis of the information from adaptive schemes,an adaptive robust state feed-back controller is designed to compensate the effects of faults and perturbations automatically.According to Lyapunov stability theory,it is shown that the robust adaptive closed-loop systems can be ensured to be asymptotically stable under the influence of actuator faults and bounded perturbations.An example is provided to further illustrate the fault compensation effectiveness.

Robust H-infinity fault-tolerant control for uncertain descriptor systems by dynamical compensators

The problem of robust H-infinity fault-tolerant control against sensor failures for a class of uncertain descriptor systems via dynamical compensators is considered. Based on H-infinity theory in descriptor systems, a sufficient condition for the existence of dynamical compensators with H-infinity fault-tolerant function is derived and expressions for the gain matrices in the compensators are presented. The dynamical compensator guarantees that the resultant colsed-loop system is admissible; furthermore, it maintains certain H-infinity norm performance in the normal condition as well as in the event of sensor failures and parameter uncertainties. A numerical example shows the effect of the proposed method.

Fault-tolerant control of linear uncertain systems using H∞ robust predictive control

The robust fault-tolerant control problem of linear uncertain systems is studied. It is shown that a solution for this problem can be obtained from a H∞ robust predictive controller （RMPC） by the method of linear matrix inequality （LMI）. This approach has the advantages of both H∞ control and MPC： the robustness and ability to handle constraints explicitly. The robust closed-loop stability of the linear uncertain system with input and output constraints is proven under an actuator and sensor faults condition. Finally, satisfactory results of simulation experiments verify the validity of this algorithm.

Output feedback based adaptive robust fault-tolerant control for a class of uncertain nonlinear systems

An adaptive robust approach for actuator fault-tolerant control of a class of uncertain nonlinear systems is proposed.The two chief ways in which the system performance can degrade following an actuator-fault are undesirable transients and unacceptably large steady-state tracking errors.Adaptive control based schemes can achieve good final tracking accuracy in spite of change in system parameters following an actuator fault,and robust control based designs can achieve guaranteed transient response.However,neither adaptive control nor robust control based fault-tolerant designs can address both the issues associated with actuator faults.In the present work,an adaptive robust fault-tolerant control scheme is claimed to solve both the problems,as it seamlessly integrates adaptive and robust control design techniques.Comparative simulation studies are performed using a nonlinear hypersonic aircraft model to show the effectiveness of the proposed scheme over a robust adaptive control based faulttolerant scheme.

Fault-tolerant Control and Disturbance Attenuation of a Class of Nonlinear Systems with Actuator and Component Failures

这份报纸象外部骚乱一样与致动器和部件失败调查非线性的动态系统的一个班的稳定问题。没有对在致动器失败变量上固定的估计的经分解的需要，新差错容忍的控制算法被导出，并且因此，结果的控制计划有更简单的结构并且作为与大多数存在方法相比要求更少的联机计算。与建议控制，致动器和分系统 / 部件失败能被提供，这被显示出，并且州的依赖生长骚乱能有效地被稀释。算法面对外部骚乱，参量的无常，以及严重致动器 / 分系统失败基于一条 Lyapunov 途径和数字模拟经由构词的数学分析被验证。

Adaptive fault-tolerant control of linear systems with actuator saturation and L_2-disturbances

This paper studies the problem of designing adaptive fault-tolerant H-infinity controllers for linear timeinvariant systems with actuator saturation. The disturbance tolerance ability of the closed-loop system is measured by an optimal index. The notion of an adaptive H-infinity performance index is proposed to describe the disturbance attenuation performances of closed-loop systems. New methods for designing indirect adaptive fault-tolerant controllers via state feedback are presented for actuator fault compensations. Based on the on-line estimation of eventual faults, the adaptive fault-tolerant controller parameters are updated automatically to compensate for the fault effects on systems. The designs are developed in the framework of the linear matrix inequality （LMI） approach, which can guarantee the disturbance tolerance ability and adaptive H-infinity performances of closed-loop systems in the cases of actuator saturation and actuator failures. An example is given to illustrate the efficiency of the design method.

Fault-tolerant decentralized H-infinity control for multi-channel systems using homotopy method

This paper considers a fault-tolerant decentralized H-infinity control problem for multi-channel linear time-invariant systems. The purpose is to design a decentralized H-infinity output feedback controller to.stabilize the given system and achieve a certain H-infinity performance requirement both in the normal situation and in the situation where any one of the local controllers fails. The designed problem is reduced to a feasibility problem of a set of bilinear matrix inequalities （BMIs）. An algorithm is proposed to solve the BMIs. First, the normal situation is considered where all the local controllers are functioning. The local controllers are obtained from a standard centralized H-infinity controller by using a homotopy method imposing a structural constraint progressively. Secondly, the above case is extended to the one where any one of the local controllers fails. We again use a homotopy method where the coefficient matrices of the failed controller are decreased progressively to zero. The efficiency of the proposed algorithm is demonstrated by an example.

Fault Tolerant Neuro-Robust Position Control of DC Motors

DC motors are widely used in industry such as mechanics, robotics, and aerospace engineering. In this paper, we present a high performance control method for position control of DC motors. Fault-tolerant control model are also addressed to combine with neuro-robust control approach. It is shown that with the proposed control algorithms, external disturbances and coupled dynamics inherent in the system are effectively compensated using neural network unit in which no analytical estimation on the upper bound of the reconstruction error and uncertainties is needed. Simulations on various flight conditions also confirm the effectiveness of the proposed methods.

Fault Tolerant Control Scheme Design for Formation Flight Control System of Multiple Unmanned Aerial Vehicles

The command tracking problem of formation flight control system(FFCS)for multiple unmanned aerial vehicles(UAVs)with sensor faults is discussed.And the objective of the addressed control problem is to design a robust fault tolerant tracking controller such that,for the disturbances and sensor faults,the closed-loop system is asymptotically stable with a given disturbance attenuation level.A robust fault tolerant tracking control scheme,combining an observer with H∞ performance,is proposed.Furthermore,it is proved that the designed controller can guarantee asymptotic stability of FFCS despite sensor faults.Finally,a simulation of two UAV formations is employed to demonstrate the effectiveness of the proposed approach.

Guaranteeing the Fault Transient Performance of Aerospace Multiphase Permanent Magnet Motor System: an Adaptive Robust Speed Control Approach

To enhance the fault transient performance of aerospace multiphase permanent magnet synchronous motor(PMSM)system,an adaptive robust speed control is proposed regardless of the phase open-circuit(OC)and short-circuit(SC)fault in this paper,which can be applied for both the redundant motor system and fault tolerant motor system.For aerospace multiphase PMSM system,besides external load disturbance and system parameter perturbation,there inevitably exists the electromagnetic torque ripple in fault transient process,which can degrade the system performance and even cause the system instability.To cope with this issue,the electromagnet torque ripple of the multiphase PMSM system in fault transient process is first analyzed.Then,by considering the electromagnet torque fluctuation caused by fault transient as a system uncertainty,a novel adaptive robust speed control scheme is proposed,while the adaptive law is constructed to emulate the total system uncertainty bound,which include the load disturbance,the parameter variation,and the electromagnetic torque fluctuation due to fault transient.The resulting control can ensure the speed control performance even in fault transient process regardless of the uncertainty,in which no prior estimation of the uncertainty bound is required.In addition,the proposed adaptive robust speed control is demonstrated by a six-phase PMSM experimental platform.The novelty of this research is to explore a novel adaptive robust speed control to strengthen the fault tolerance performance of multiphase PMSM system even in fault transient process,which requires no prior estimation of the uncertainty bound.

容错控制系统鲁棒H_∞和自适应补偿设计

通过设计动态输出反馈控制策略研究线性时不变系统执行器故障下的鲁棒自适应容错H∞控制问题.结合自适应技术和线性矩阵不等式(Linear matrix inequalities,LMI)技术,设计一个控制策略同时实现系统的故障补偿控制和性能优化控制.在设计中,提出由自适应律在线调节控制增益方程补偿未知执行器故障和摄动;并设计一个基于模式依赖李亚普诺夫方程的LMI条件解出控制参数及次优H∞性能.所设计的动态输出反馈控制器可以处理一般执行器卡死故障,并得到更少保守性的H∞性能指标.此外,一个更具挑战性的问题,即通过自适应机构补偿故障致使系统多少性能退化得到论证.所提方法的有效性由一个解耦线性化动态飞行器系统仿真验证.

网络控制系统的鲁棒H_∞容错控制器设计

研究了一类网络控制系统(NCS)的鲁棒H∞容错控制器设计问题.基于一类包含网络时延和数据包丢失的网络控制系统模型,考虑了更实际、更一般的执行器部分失效情况.然后利用Lyapunov Krasovskii泛函方法,通过引入一个积分不等式,得到了此类系统的H∞鲁棒稳定性条件并且采用锥补线性化算法给出了此类系统的鲁棒H∞容错控制器的设计方法.最后,数例仿真结果表明,对于任意容许的不确定性以及执行器的故障,所设计的控制器能使系统鲁棒渐近稳定,且具有H∞范数界.

风能转换系统随机建模与H_∞容错控制

针对带有传感器、执行器故障的风能转换系统(WECS)的建模与容错控制问题,提出了基于随机分段仿射(PWA)模型的建模方法和H∞容错控制方法。建立了风电机组多工作区域的随机PWA正常模型;针对WECS的桨距角传感器故障、功率测量传感器故障、桨距角执行器故障、电机电磁转矩执行器故障,建立风能转换系统的随机PWA故障模型;基于WECS系统的正常和故障的随机PWA模型,利用非线性耗散系统的稳定性理论与H∞鲁棒控制方法,提出并证明了WECS系统的H∞容错控制器存在性定理,给出控制器求解方法。仿真结果表明本文所提出的基于随机PWA模型的风能转换系统的H∞容错控制方法对于存在的传感器、执行器增益故障具有较好的容错控制性能。

基于混合H_2H_∞的集成故障诊断与容错控制研究

研究了一类线性不确定系统的集成故障诊断与容错控制。针对执行机构和敏感器故障,考虑故障诊断结果的不确定性与系统参数的不确定性,分别采用H2和H∞范数作为系统故障诊断和容错控制的性能指标,设计输出反馈混合H2/H∞控制律,运用线性矩阵不等式(LMI)方法求解集成故障诊断与容错控制问题。最后,建立卫星闭环姿态控制系统对算法进行了仿真验证,仿真结果验证了方法的有效性。

航空发动机分布式控制系统不确定性鲁棒H_∞容错控制

为减小不确定性对航空发动机分布式控制系统性能的影响,针对具有参数摄动、不确定时延、执行机构动态故障、外部噪声干扰四种不确定性的航空发动机分布式控制系统,提出了一种基于鲁棒H∞理论的容错控制方法。首先对系统不确定性进行数学描述,将不确定时延视为服从齐次Markov链分布的随机变量,将执行机构故障等效为存在均值和方差约束的随机变量,并在此基础上建立整个闭环系统的增广模型;其次证明了该增广模型保持均方渐进稳定且具备H∞性能的充分条件;最后利用线性矩阵不等式(LMI)理论给出闭环系统鲁棒H∞容错控制器的设计方法。仿真结果表明该方法能够保证控制系统均方渐进稳定,并对以上四种不确定因素具有鲁棒性,同时对于飞行包线其他各点具有较好的动态响应。

基于T-S模糊模型的网络控制系统鲁棒H_∞容错控制

针对同时存在网络时延和数据包丢失的网络环境,研究了执行器故障下一类非线性网络控制系统的鲁棒H∞容错控制问题。基于不确定T-S模糊模型描述的非线性网络控制系统模型,考虑了更实际、更常见的执行器部分失效情况。通过引入一个积分不等式,获得了此类系统的时滞相关鲁棒稳定性条件,且采用锥补线性化算法给出了此类系统的鲁棒H∞容错控制器设计方法。仿真算例表明,对于任意容许的不确定性以及执行器故障,所设计的控制器能使系统鲁棒渐近稳定,且具有H∞范数界。

参数不确定性时滞系统的鲁棒H_∞ 容错控制器设计(英文)

研究了一类同时具有参数不确定性、外界干扰和时滞的线性系统执行器失效的问题 .给出了该类系统一种鲁棒H∞ 容错控制器的设计方法 .通过假设失效执行器的输出信号是任意能量有界的干扰信号 ,不确定线性时滞系统的容错控制问题转化成了鲁棒H∞ 控制问题 .控制器可以通过解修正的代数黎卡提方程得到 ,而且控制器与时滞常数无关 .设计例子证明了所给方法的有效性 .

基于H_2/H_∞控制的汽车主动悬架最优鲁棒容错控制

为提高汽车主动悬架控制可靠性和控制效果,针对悬架参数摄动和作动器故障,提出一种基于H2/H∞的最优鲁棒容错控制方法。考虑作动器常见故障、悬架刚度与阻尼系数摄动,建立故障悬架模型。基于H2/H∞状态反馈控制,利用有界实引定理推导出悬架最优鲁棒容错控制器设计条件。运用LMI工具箱离线设计控制器,并在MATLAB/Simulink环境下进行大量仿真计算。结果表明,设计的最优鲁棒容错控制器能改善汽车主动悬架乘坐舒适性,亦能改善故障悬架乘坐舒适性,且在控制效果上均优于完好无故障状态下设计的控制器。